Install fails if SSH server not present

[nikolajsheller]

Problem:

Fresh install of v61.1 fails on fresh ubuntu 22.04 if openssh-server not installed.

Symptom:

No error is shown and no indication is given as to the cause of installation failure.

Specifically this line fails:

setup/system.sh
SSH_PORT=$(sshd -T 2>/dev/null | grep "^port " | sed "s/port //") #NODOC

Root cause:

I saw this on an LXD container, where I accessed the console though LXD, without needing SSH.
openssh-server is not installed during MIAB setup, and no check is performed to see if openssh-server is present, causing installation to break in a very non-obvious manner.

Solution proposal:

I think installing openssh-server by default, prior to detecting the SSH port, would solve the issue.

It would e.g have prevented these problems:
https://discourse.mailinabox.email/t/installation-quits-at-initializing-system-random-number-generator/4581
https://discourse.mailinabox.email/t/installing-miab-v61-1-on-ubuntu-22-04-hostinger-vps-1/10283/3